Abrasive articles are used in a variety of industrial applications for modifying (e.g., abrading, finishing, polishing, planarizing, etc.) surfaces during various phases of manufacture. For example, in manufacturing semiconductor devices, a wafer typically undergoes numerous processing steps, including deposition, patterning, and etching. After one or more of these processing steps it is necessary to achieve a high level of surface planarity and uniformity.
A conventional surface modifying technique comprises polishing, e.g., the chemical mechanical polishing (CMP) of a semiconductor wafer, wherein a wafer in a carrier assembly is rotated in contact with a polishing pad in a CMP apparatus. The polishing pad is mounted on a turntable or platen. The wafer is mounted on a rotating/moving carrier or polishing head, and a controllable force presses the wafer against the rotating polishing pad. Thus, the CMP apparatus produces polishing or rubbing movement between the surface of the wafer and the polishing pad. Optionally, polishing slurry containing abrasive particles in a solution can be dispersed on the pad and wafer. Typical CMP can be performed not only on a silicon wafer itself, but also on various dielectric layers, e.g., silicon oxide; conductive layers, e.g., aluminum and copper; or layers containing both conductive and dielectric materials, as in Damascene processing.
Chemical mechanical polishing may also be conducted using a fixed abrasive article, e.g., a fixed abrasive polishing sheet or fixed abrasive pad. Such a fixed abrasive article typically comprises a plurality of abrasive composites optionally adhered to a backing. The abrasive composites may comprise abrasive particles in a binder, e.g., a polymeric binder. A working fluid may be used with the fixed abrasive article and the wafer. A chemical agent can be provided, e.g., in a working fluid or incorporated in the fixed abrasive article, to provide chemical activity, while the fixed abrasive composites provide mechanical activity and, in some processes, chemical activity.
During CMP, the abrasive article becomes less active, i.e., the abrasive article becomes less effective at modifying the surface of a substrate. For example, as the abrasive article modifies the surface of a substrate, abrasive particles may be removed from the abrasive composites. As abrasive particles are removed from the abrasive composites, the rate of CMP may be reduced as the fixed abrasive article becomes less effective at providing mechanical and/or chemical activity. Also, abrasive particles remaining in the abrasive composites may become less active, e.g., less mechanically and/or chemically active. If these spent abrasive particles are not removed from the abrasive composites, the rate of CMP may be reduced as the fixed abrasive article becomes less effective at providing mechanical and/or chemical activity.